多波段鱼眼镜头相机实验室几何定标方法  

Laboratory Geometric Calibration Method for Multi-band Fisheye Lens Camera

作　　者：王彩霞 陈洪耀 司孝龙[1] 李鑫[1] 李佳伟 张黎明[1] 包诗薇 WANG Caixia;CHEN Hongyao;SI Xiaolong;LI Xin;LI Jiawei;ZHANG Liming;BAO Shiwei(Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China;University of Science of and Technology of China,Hefei 230026,China)

机构地区：[1]中国科学院合肥物质科学研究院安徽光学精密机械研究所,合肥230031 [2]中国科学技术大学,合肥230026

出　　处：《光子学报》2024年第8期180-193,共14页Acta Photonica Sinica

基　　金：中国科学院科研装备研制项目(No.YZ201125)。

摘　　要：鱼眼镜头因其独特的曲率和光学特性,使用非相似成像模型拟合后,仍有接近10像素的径向残余畸变。研究了多波段鱼眼相机的定标原理、定标流程,在非相似成像模型基础上,提出了基于分离式精密二维转台的鱼眼镜头定标方法,并通过相机姿态位置精密调整与方位转台360°旋转,光斑像素位置始终不变的方法,确定相机主点。为分析色差对鱼眼镜头径向畸变的影响,采取不同波段单独定标的方法。利用不同时刻的太阳角度数据来验证镜头定标系数,结果显示天顶角与方位角的均方根误差分别为0.226°和0.487°。该方法有效实现了鱼眼镜头相机在不同波段的几何定标,提高了像素点与入射光线角度之间的匹配精度。The significant distortion introduced by fisheye lenses,while expanding the field of view,poses a new scientific problem:the projection process cannot be described using traditional pinhole photography models.To obtain the mapping relationship between pixel points and the angle of incident light,it is necessary to reconstruct the imaging model based on the unique nonlinear distortion characteristics of fisheye cameras.However,due to their unique curvature and optical characteristics,even the common universal models cannot completely eliminate radial residual distortion,with errors reaching nearly 10 pixels.Also,due to the chromatic aberration characteristics of fisheye lenses,there are differences in the refraction of light in different bands.This article studies the calibration principle and calibration process of multi-band fisheye cameras,proposing a fisheye lens calibration method based on a separated precision two-dimensional turntable.The rotary indexing table and the vertical turntable have good repeated positioning accuracy,which are 2 s and 10.8 s respectively,and the orthogonal error of the two rotation axes is less than 10 s.Both drive the camera and collimator to rotate,so that the light spot covers the entire field of view of the lens.To simplify the coordinate conversion process,it is necessary to adjust the collimator to align its optical axis perpendicular to the rotation axis of the rotary indexing table.According to the theory that an ideal lens can focus parallel light from an infinite distance on the main point,fine-tune the camera's position and posture until the camera rotates around the Z-axis from 0°to 360°,and the position of the spot on the image remains unchanged.At this point,the centroid coordinates of the spot are the pixel coordinates of the main point.On this basis,a fifth-degree polynomial is used to fit the residuals and describe the camera projection process together with an equisolid angle projection.The five bands from visible light to near-infrared are calibrated separately

关 键 词：鱼眼镜头 几何定标 畸变矫正 全天空成像 天空辐亮度分布 

分 类 号：TP79[自动化与计算机技术—检测技术与自动化装置]